Safety Instructions - Beko K1 CHASSIS Service Manual

1.

SAFETY INSTRUCTIONS

GENERAL GUIDELINES
1. It is advised to insert an isolation transformer
in the AC supply before servicing a hot
chassis.
2. Potentials as high as 33KV are present when
this receiver is in operation. Operation of the
receiver without the rear cover involves the
danger of a shock hazard from the receiver
power supply. Servicing should not be
attempted by any one who is not competent
with the precautions necessary when working
on the high voltage equipment. Always
discharge the anode of the tube.
3. When servicing observe the original lead
dress in the high voltage circuits. If a short
circuit is found, replace all the parts which
have been overheated or damaged by the
short circuit.
4. Always use the manufacturer's replacement
safety components.
components
schematics diagrams should not be replaced
by other substitutes. Other substitute may
create the electrical shock, fire or other
hazards. Take attention to replace the
spacers with the originals. Furthermore where
a short circuit has occurred, replace those
components
overheating.
5. After servicing, see that all the protective
devices such as insulation barriers, insulation
papers, shields
combinations are correctly installed.
6. When the receiver is not being used for a
long time of period of time, unplug the
power cord from the AC outlet.
7. After servicing make the following leakage
current checks to prevent the customer from
being exposed to shock hazard.
LEAKAGE CURRENT COLD CHECK
1. Unplug the AC cord and connect a jumper
between the two prongs of the plug.
2. Turn the receiver's power switch on.
3. Measure the
ohmmeter, between the jumpered AC plug
and each exposed metallic cabinet part on
the receiver, such as screw heads, aerials,
connectors, control shafts etc. When the
The critical
marked with
that indicate evidence
and isolation
resistance value with
LEAKAGE CURRENT HOT CHECK
1. Plug the AC cord directly in to the AC outlet.
2. Connect a 2Kohm 10W resistor in series with
3. Use an AC voltmeter with high impedance to
4. Check each exposed metallic part and
5. Reverse the AC plug at the outlet and repeat
6. The potential at the any point should not
safety
on the
HOT CHECK CIRCUIT
of
TO INSTRUMENTS
EXPOSED
METALLIC PARTS
R-C
X-RAY RADIATION WARNING
The primary source of X-ray radiation in this receiver
is the picture tube. The chassis is specially
constructed to limit X-ray radiation. For continued X-
ray radiation protection, replace the tube with the
same type of the original one.
CAUTION
AFTER REMOVAL OF THE ANODE CAP, DISCHARGE THE
ANODE OF THE PICTURE TUBE AND THE ANODE CAP TO
THE METAL CHASSIS, CRT SHIELD, OR THE CARBON
an
PAINTED ON THE CRT WITH A HIGH VOLTAGE PROBE
AND MULTIMETER (SELECT VDC) AND THEN SHORT
CIRCUIT DIRECTLY TO DISCHARGE COMPLETELY
2
exposed metallic part a return path to the
chassis the reading should be between
4Mohm and the 20Mohm. When the exposed
metal does not have a return path to the
chassis, the reading must be infinite.
Do not use an isolation transformer for this
check.
an exposed metallic part on the receiver and
an earth, such as a water pipe.
measure the potential across the resistor.
check the voltage at the each point.
each of the above measurements.
exceed 1.4 Vrms. In case a measurement is
outside the limits specified, there is the
possibility of a shock hazard, and the receiver
should be repaired and rechecked before it
is returned to the customer.
AC-Voltmeter
2 K Ohm
Figure 1
.
Water pipe
(earth)